by Michael E. Pichichero, M.D.
Professor of Microbiology and Immunology, Pediatrics and Medicine
University of Rochester Medical Center
Elmwood Pediatric Group

What is Strep Throat?

Streptococcal pharyngitis ("strep throat") is one of the most common bacterial infections in children. Although there are over 20 types of streptococci, the group A strain is the most frequently encountered as a cause of sore throat. The changes of acute strep throat are confined to the tonsils, back of the throat, and the draining lymph nodes in the front of the neck. Changes in the infected tissues reflect an inflammation which produces redness, swelling, and pus on the surface of the tonsils and back of the throat.

Blisters and ulcers are uncommon. In infants, the nose is more typically involved in the infection as opposed to the throat. Infection may be transferred from the back of the throat or the nose to the skin, causing facial impetigo. Localized extension of strep may occur to adjacent cites to include the sinuses, the middle ear (acute ear infection), the epiglottis, and regional lymph nodes. Further extension may lead to meningitis in rare cases.

What causes sore throats?

The largest proportion of children (15-40%) and adolescents (30-60%) with sore throat have a viral infection. About 8-30% of children and 5-9% of teenagers with fever and throat inflammation have a strep infection. Other bacteria infrequently cause throat infection. Particularly among teenagers, the differential diagnosis includes other species of streptococci (group C and group G) and even the possibility of gonococci (gonorrhea germ) causing a sore throat. Other bacteria include Mycoplasma pneumoniae, Chlamydia pneumoniae and Arcanobacterium haemolyticum as causes of symptomatic sore throat.

In developing countries, diphtheria remains a cause of sore throat. Very often sore throats are of unknown course and this may represent viruses which at present cannot be identified, post nasal drip, allergy, etc.

Who gets strep throat?

Strep throat infections are spread person-to-person. Humans are the natural reservoir of this bacteria. The nose and back of the throat are the main sources of carriage of this bacteria. The skin and feces are potential sites. Aerosolized upper respiratory mucus serves as the primary source of the strep germ spreading to others. Direct contact with infected nose and throat tissues (by kissing) is of less importance as is contact with contaminated objects, such as toothbrushes.

Spread of strep throat requires the presence of a susceptible child and is facilitated by close contact.

Acquisition of infection is rare in infancy due to mothers' immunity conferred transplacentally. Infection is uncommon below the age of two years. When infection occurs during the toddler years, it most often involves the nose. Children in day care and grade school more frequently contract and spread strep throat. Teenagers and adults usually have had contacts with the bacteria over time to provide immunity, thereby rendering strep uncommon in these age groups.

How does strep cause disease?

Strep produces a self-limited localized inflammation of the throat, generally lasting 3-5 days. Antibiotic treatment, if prompt and appropriate, reduces the duration of symptoms, shortens the period of contagion and reduces the risk of localized spread and complications. A major objective of administering antibiotics is to prevent rheumatic fever and possibly reduce the occurrence of post-strep kidney damage.

Common findings

Strep throat cannot be accurately diagnosed on the basis of history and examination in most patients. Classically, strep throat patients have fever, redness and swelling of the throat with pus on the tonsils and back of the throat. Swollen and tender lymph nodes in the front of the neck typically occur. It is quite unusual for a patient with strep throat to also have a runny nose and a cough. Strep throat occurs most commonly in mid-winter to early spring. If all of the typical history and symptoms of strep throat are present, then the likelihood of strep approaches 60-70% in children and 20-30% in teenagers.

How do you diagnose strep throat?

In 1954, the first reports of using a throat culture in an office setting initiated an era of office based laboratory diagnosis for pediatricians and family doctors. The use of a throat culture to confirm the presence of strep throat has become a common practice and has grown steadily such that by the early 1980's the Centers for Disease Control estimated that between 28-36 million throat cultures were performed annually in the United States. The value of this simple laboratory test in avoiding unnecessary antibiotics and in identifying children and teenagers requiring treatment is considerable.

Rapid strep detection tests came into wide use in the 1990's. These tests can be performed quickly at a cost that is comparable to a 10 days supply of penicillin. These tests, if properly performed, have the same reliability as a throat culture.

Treatment

Treatment should relieve the symptoms of acute strep throat, eliminate transmission and prevent complications. Ideally, the chosen antibiotic should be easy to administer free of side effects and affordable. None of the antibiotics used in the treatment of strep throat achieves all of these goals in all infected patients-including penicillin which is the gold standard of therapy. In considering treatment of strep throat, the physician is faced with a large number of generic and brand name antibiotics with wide ranges of effectiveness, side effects and costs.

Strep germs are highly susceptible to penicillin, amoxicillin, Augmentin, and the cephalosporins (Keflex, Duracef, Ceclor, Lorabid, Cefzil, Ceftin, Vantin, Omnicef and Cedax). 90-95% of strep strains are susceptible to erythromycin, Biaxin, Zithromax and Cleocin. Ten days of oral penicillin and erythromycin are necessary to achieve a maximum cure of strep throat. However, completion of 10 days therapy is often problematic as parents and teenagers forget to administer or take the antibiotic as symptoms improve over the first few day of treatment.

A five day course of therapy with several cephalosporins has been shown to produce a similar or superior cure compared with 10 days of oral penicillin. The cephalosporins tested for five days include Duracef, Ceftin, Vantin and Omnicef. Zithromax may be administered for five days because the antibiotic persists in the throat tissues for five days after discontinuation of the drug.

What are the complications of strep throat?

The main concern with strep throat relates to the development of acute rheumatic fever. This is an infection of the heart valves which leads to permanent heart valve damage with the possibility of progression to heart failure. Strep throat also causes kidney damage if not prevented by use of antibiotics. The kidney damage of the filtering system can lead to both acute kidney failure and chronic kidney problems. Of course, strep can also spread to tissues in the upper airways (for example, deep throat infections and infections of the draining lymph nodes at the front of the neck. Extension from the throat to the brain rarely occurs thereby producing meningitis or brain abscess.

How do you prevent strep complications?

Antibiotics, if promptly initiated, will prevent virtually all of the complications of strep. Rheumatic fever can be prevented if antibiotic therapy is begun within 9 days of the onset of first symptoms.

What research is being done?

New antibiotics are usually tested for their effectiveness in the treatment of strep throat and antibiotics which can be administered for shorter durations of time do represent the possibility of a treatment advance because of the tendency for everyone to prefer shorter treatment durations for a complete cure. Vaccines for the prevention of strep throat have now reached clinical studies in humans. The difficulty in development of an effective vaccine for strep throat has been the diversity of strep strains.

Dr. Michael E. Pichichero is currently a Professor of Microbiology and Immunology, Pediatrics and Medicine at the University of Rochester in Rochester, NY.

A graduate of the University of Rochester School of Medicine, Dr. Pichichero completed his postgraduate pediatric residency at the University of Colorado in Denver, followed by a Chief Residency and two fellowships resulting in board certification in Pediatrics, in Adult and Pediatric Allergy and Immunology and in Pediatric Infectious Disease.

Dr. Pichichero is a partner in the Elmwood Pediatric Group where he continues to practice in primary care and as a subspecialist consultant.

A recipient of numerous awards and a member of most professional societies in his fields of interest, Mike has over 300 publications in infectious diseases, immunology, and allergy.

His major practice and research interests are in vaccine development, streptococcal infections, and otitis media: in each of these areas he is a prominent international authority.